BOOSTER SHOTS: Oddities, musings and news from the health world

Probiotics could someday treat depression and anxiety

Lactobacillus in the gut may be helpful for the brain. The bacteria helped… (Anne C. Smith/MicrobeLibrary.org )

What if you could treat depression, anxiety and other mood disorders without drugs or invasive procedures but simply by eating probiotic yogurt, or drinking a probiotic broth? A new study in mice suggests this may be possible someday.

An international team of researchers found that mice who drank a broth spiked with the organism Lactobacillus rhamnosus (JB-1) were less likely to be anxious or stressed than control mice who drank a bacteria-free broth. The mice who drank the probiotic broth also produced less of the stress hormone corticosterone in their brains in response to a stressful event compared with the control group of mice.

A link between the gut and the brain may sound strange, but it shouldn’t come as a surprise to anyone who has ever had a queasy stomach before a nerve-racking event, like taking an important exam or delivering a speech to a room full of people.

The researchers believe the vagus nerve plays a key role in allowing bacteria in the gut to influence the brain. In their experiments, L. rhamnosus (JB-1) was helpful only in mice with an intact vagus nerve, not in mice who had a portion of the nerve removed. It appears that the gut bacteria helped normalize the expression of important neurotransmitters in the brain that would naturally be turned up or turned down when animals become stressed or anxious.

This doesn’t mean that people with mood problems should start taking probiotic supplements or buying up crates of probiotic yogurt. In the experiments the researchers found that while L. rhamnosus (JB-1) made a difference to lab mice, another strain of bacteria called Lactobacillus salivarius had no effect. The probiotics in Dannon’s Activia yogurt and Yoplait’s YoPlus yogurt are in the Bifidobacterium genus, according to the companies’ websites.

The study was published online Monday by Proceedings of the National Academy of Science.